Were you seeing some Data in the dashboards before or has this message always shown up since you deployed the Firepower solution? If this was showing something before and stopped working, first verify that the Firepower Manager can talk to the Sensor/Appliance and the devices are synced. If all this looks good, it could a problem with certain services not functioning- at which point opening a TAC case would be the best option to fix this.
IF this is new deployment, then first check if the sensor and FMC is synced with regards to registration and policies. Once synced, make sure the sensor (say SFR module on the ASA) is configured to receive the right traffic from the network device (ASA in this case). If the sensor is receiving data and it is synced with the FMC, data should start to show in the Dashboards.